The present invention relates to systems by which the location and orientation of an element in space (e.g. a robot arm or other platform) can be accurately determined by electrooptical means. The invention has applications either in open loop position locating systems or in closed loop position control systems such as may be used for the accurate control of robotic arms.
One of the more difficult current technological problems is to locate and orient a robotic arm with an accuracy sufficient to perform the tasks required. Such tasks might include the accurate drilling of holes, matching of surfaces or insertion of parts in predetermined positions. Many of these tasks require positioning accuracies greater than those presently achievable by the open-loop servo-mechanism controls presently employed. Most of the prior-art inaccuracies are traceable to the effects of the gravitational force vector on the robot arm, which acts to offset the arm position from that designated by the servo-mechanism controls.